This invention relates to organic stripping compositions containing methylene chloride and methane sulfonic acid which are useful in removing polymeric organic substances such as photoresists, rubber adhesives, etc. from inorganic substrates.
During manufacture of semi-conductors and semi-conductor microcircuits, it is frequently necessary to coat the materials from which the semi-conductors and microcircuits are manufactured with a polymeric organic substance which is generally a photoresist, i.e., a substance which forms an etch resist upon exposure to light. Subsequently, the polymeric organic substance must be removed from the surface of the inorganic substrate which is typically a silicon dioxide coated silicone wafer and may also contain metallic microcircuitry, such as aluminum, on the surface. Therefore, there is need for improved stripping compositions which will remove the polymeric organic substance from the coated inorganic substrate without corroding, dissolving or dulling the surface of the metallic circuitry or chemically altering the inorganic substrate.
Prior art methods are known for removing such polymeric organic substances by use of organic compositions containing phenol and linear alkylbenzenesulfonic acids, as exemplified in U.S. Pat. No. 3,871,928 (Schevey, Kremers to Allied Chemical, issued March, 1975) or containing linear alkylbenzenesulfonic acids and aromatic, aliphatic or chlorinated aliphatic and aromatic solvents, as disclosed in U.S. Pat. No. 4,242,218 (Vander Mey to Allied Chemical, issued December, 1980).
Stripping compositions containing tetrachloroethylene, and ortho-dichlorobenzene, dodecyl sulfonic acid, and formic acid are disclosed in U.S. Pat. No. 4,187,191 (Simpson to General Motors, issued Feb. 5, 1980).
Stripping solutions containing a surfactant, alkylarylsulfonic acid, a hydrotropic aromatic sulfonic acid and a halogen-free aromatic hydrocarbon solvent with a boiling point above 150.degree. C. are disclosed in U.S. Pat. No. 4,165,294 (Vander Mey to Allied Chemical, issued, August 1979).
Organic compositions containing at least about 0.05% of anhydrous hydrofluoric acid as a stripping agent and organic solvents and solubilizing agents for the hydrofluoric acid, for removing paint from metallic surfaces, are known in the prior art, as exemplified in U.S. Pat. No. 3,335,087 (Keers to Pennsalt, issued August, 1967), and U.S. Pat. No. 3,335,088 (Mandell to Pennsalt, issued August, 1967).
In U.S. Pat. No. 4,165,295 (Vander Mey to Applied Chemical, issued August, 1979) there is disclosed an improved organic stripping composition useful for removing organic polymeric substances and photoresist, and containing alkylsulfonic or monoalkylarylsulfonic acid, an aromatic or isoparaffin hydrocarbon solvent, optionally phenol and stabilized against metal corrosion by addition thereto of 5 to 250 ppm of fluoride ion.
Prior art inorganic stripping compositions for removing polymeric organic substances comprise aqueous sulfuric acid compositions containing at least about 300 ppm of fluoride ion to reduce metallic dulling and corrosion, as exemplified in U.S. Pat. No. 3,932,130 (Bennett, Brockington to Texaco, issued January, 1976), U.S. Pat. No. 3,654,001 (Mann to North American Rockwell, issued April 1972) and U.S. Pat. No. 3,060,071 (Kinder to Allied Chemical, issued October 1962).
However, some of the above-mentioned photoresist removal applications require the presence of fluoride ion stabilizers to prevent metallic, especially aluminum corrosion. Furthermore, most of these organic stripping compositions operate at elevated temperatures.
It is an object of this invention to provide an organic stripping composition which operates without added flouride ion at room temperature to cleanly, effectively and quickly remove organic photoresist materials from metallized inorganic substrates, particularly aluminized silicon dioxide, without causing substantial etching of the inorganic substrate or corrosion and dulling of the metallic circuitry on the surface of the inorganic substrate. It is also an object of this invention to provide a method for removing polymeric organic substances, rubber adhesives and the like from substances of metallized inorganic substances or metals particularly aluminum or aluminized silicon dioxide, without causing etching of the metal or the inorganic substrate or corrosion and dulling of the metallic circuitry on the surface of the inorganic substrate.